Temperature responsive throttling valve

ABSTRACT

The present disclosure relates to an automotive air conditioner system which is arranged to have a throttle valve including a temperature-responsive power operating means situated in the refrigerant suction line for throttling refrigerant flow from the evaporator when the evaporator temperature drops toward a value low enough to cause ice formation on the evaporator fin surfaces. The throttle valve is preferably but not necessarily located upstream of the actuator means of the thermostatic expansion valve. The power operating temperature responsive means includes a wax filled container and a slidable piston which cooperatively move a valve member toward a valve seat when the temperature of the refrigerant in the suction line decreases to a moisture freezing level. The throttling effect prevents the compressor from pulling down the pressure and temperature within the evaporator to a level where ice or frost could form on the surfaces of the fins of the evaporator.

United States Patent [1 1 Proctor TEMPERATURE RESPONSIVE THROTTLING VALVE [75] Inventor: Robert H. Proctor, Richmond, Ind.

[73] Assignee: Jackes-Evans Manufacturing Company, St. Louis, Mo.

[22] Filed: Dec. 4, 1970 [21] Appl. No.: 95,260

Related US. Application Data [63] Continuation-impart of Ser. No. 75,713, Sept. 25, 1970, Pat. No. 3,691,783, which is a continuation of Ser. No. 795,828, Feb. 3, I969.

[52] US. Cl 236/34, 62/212, 62/217, 62/224 [51] Int. Cl. F25b 41/04 [58] Field of Search 236/92, 93, 99, 100, 236/101', 34, 34.5

[56] References Cited UNITED STATES PATENTS 3,075,703 l/l963 Freismuth 236/34 3,533,552 10/1970 Schercr 236/34 3,591,075

7/1971 Onishi 236/34 10 Comprersan l2 C'ondenrec' 14 Receiver.

Primary ExaminerMeyer Perlin Att0rney-Robert E. Wagner 5 7 ABSTRACT The present disclosure relates to an automotive air conditioner system which is arranged to have a throttle valve including a temperature-responsive power operating means situated in the refrigerant suction line for throttling refrigerant flow from the evaporator when the evaporator temperature drops toward a value low enough to cause ice formation on the evaporator fin surfaces. The throttle valve is preferably but not necessarily located upstream of the actuator means of the thermostatic expansion valve. The power operating temperature responsive means includes a wax filled container and a slidable piston. which cooperatively movea valve member toward a valve seat when the temperature of the refrigerant in the suction line decreases to a moisture freezing level. The throttling effect prevents the compressor from pulling down the pressure and temperature within the evaporator to a level where ice or frost could form on the surfaces of the fins of the evaporator.

9 Claims, 3 Drawing Figures breasm PATENIEDJAN 1 5 mm m @m w WMQ Q Q WMQQQQQ QN 1 TEMPERATURE RESPONSIVE THROTTLING VALVE This application is a continuation-in-part of application Ser. No. 75,713, filed Sept. 25, 1970 for Refrigerant Evaporator Temperature Control now US. Pat. No. 3,691,783 issued Sept. 19, 1972 which, in turn was a continuation of Ser. No. 795,828, filed Feb. 3, 1969 I for Refrigerant Evaporator Temperature Control and now abandoned.

This invention relates to an improved throttling valve, and more particularly to a throttle valve for throttling the flow of refrigerant leaving an evaporator of a refrigerating system so that ice is prevented from being formed on the surfaces of the fins of the evaporator during high humidity and low load demand conditions.

In refrigerating systems, such as automotive air conditioners, frost or ice formation of the surfaces of the fins of the evaporator results in inefficient operation as well as causes an annoyance to vehicle owners. Since an automotive air conditioner is exposed to all types of environmental conditions and is required to operate under various load demands at a wide range of engine speeds, it was common for the evaporator to become iced and frosted. This frosted condition normally occurs when the humidity is relatively high and when the load demand is decreased. Under these circumstances, the decrease in load causes the pressure of the evaporator to be sharply pulled down by the compressor. The drop in evaporator pressure is accompanied by a drop in temperature of the refrigerant which at approximately 32 F allows the moisture in the air to form frost and ice on the fins of the evaporator. If the build-up continues, the fins will eventually become completely clogged with ice so that no air will be able to pass through the evaporator and substantially no cooling will result from the air conditioner. In order to prevent such adverse operations, it is necessary to preclude a pressure drop in the evaporator during reduced load demand periods. It has been found that by measuring the temperature of the refrigerant flowing in the suction line, it is possible to prevent ice from forming on the evaporator by a throttling operation. That is, if a suitable temperature responsive throttle valve is placed in the suction line, throttling action is arranged to begin at approximately 39 F and continues so that no further drop in evaporator pressure and no further accompanying drop in temperature of the refrigerant can be caused by the lightly loaded compressor. Thus, the temperature of the evaporator can be maintained above the level at which the moisture of the air could form ice and frost on the surfaces of the fins.

Accordingly, it is an object of this invention to provide a temperature responsive throttling valve for regulating the flow of fluid refrigerant in an air conditioner system.

Another object of this invention is to provide a throttling means in the suction line ofa refrigerating system having a continuously running refrigerant compressor, condenser, evaporator, refrigerant meter means between the condenser and evaporator.

A further object of this invention is to provide a throttling valve which is responsively controlled by a decrease in temperature of the refrigerant in the suction line for throttling the flow of refrigerant leaving the evaporator in order to prevent the formation of ice thereon.

Yet another object of this invention is to provide a new and improved valve which is temperatureresponsive to throttle the flow of fluid.

Yet a further object of this invention is to provide a throttle valve which is responsive to a decrease in temperature to throttle the flow of a fluid.

Still another object of this invention is to provide a throttle valve having a temperature responsive power operating means for controlling the flow of refrigerant in a closed refrigerating system.

Still a further object of this invention is to provide an evaporator temperature regulator which throttles the refrigerant leaving the evaporator in accordance with the temperature of the refrigerant so that ice will not be formed on the surfaces of the fins of the evaporator.

Still yet another object of this invention is to provide a throttle valve having a temperature sensitive power operating means which includes a container and a slidable piston which cooperatively move a valve member toward a valve seat when the temperature of a fluid decreases within a temperature range and which cooperatively move the valve member away from the valve seat when the temperature of a fluid increases within the temperature range.

Still yet a further object of this invention is to provide a temperature responsive throttle valve for a refrigerating system which is economical in cost, simple in construction, reliable in operation, durable in use and efficient in service.

In accordance with the present invention, a throttle valve is situated in the suction line of an air conditioner system having a continuous running refrigerant compressor, a condenser, an evaporator and refrigerant metering device located between the condenser and evaporator. The throttle valve includes a cylindrical valve body having an inlet and an outlet. A temperature responsive power operating means includes a container and slidable member which are fixedly mounted within the valve body. The container includes a mass of temperature sensitive material which expands and contracts in accordance with temperature changes which thereby allows relative movement to occur between the container and the slidable member. A valve member is carried by the power operating means and an associated valve seat is disposed within the valve body. The valve member is constantly urged toward the valve seat by biasing spring. During normal operation, the valve member is unseated due to the expanded condition of the mass of temperature sensitive material which overcomes the efforts of the biasing spring and extends the slidable member. However, when the temperature of the refrigerant in the suction line drops to a preselected level the mass of temperature sensitive material contracts and the spring depresses the slidable member into the container and urges the valve member toward the valve seat so that flow of refrigerant from the evaporator is throttled. The throttling action prevents the compressor from reducing the pressure and temperature of the evaporator to a level where ice or frost could form on the fins of the evaporator.

The foregoing objects and other attendant features and advantages will be more readily appreciated as the subject invention becomes better understood by reference to the followingdetailed description when consid ered in conjunction with the accompanying drawings wherein:

FIGv l, partly schematic, shows one form in which the invention can be practiced.

FIG. 2 is a chart showing temperature-pressure conditions in a system using the FIG. 1 apparatus.

FIG. 3 is a temperature-motion diagram for a thermostatic power means usable in the FIG. 1 apparatus.

In viewing the drawings, and in particular FIG. 1, there is shown an automotive air conditioner system comprising a refrigerant compressor driven from the engine through a suitable clutch (not shown), a refrigerant condenser 12, receiver 14, expansion valve 18 and evaporator 16. Valve 18 comprises a ported body 20 permanently assembled into the refrigerant system, and a removable valve cartridge 22 having a thermostatic actuator means 24. The actuator means 24 in-' cludes a sleeve 26 permanently affixed to the cartridge, as by the staking at 28, a lower cap 29, a metallic diaphragm 30, and an upper cap 32, the various members being welded together by a continuous peripheral weld 34. The space between diaphragm 30 and cap 32 is occupied by a thermally expansible material 36, for example, the same material used in the refrigerant system. Thermal insulation is provided at 37 to insulate the charge from the ambient temperature.

During operation of the system the refrigerant issues from the evaporator outlet in gaseous form at a superheat determined by the adjustment of a spring 38 within the expansion valve. The superheat control occurs as a result of the opposing forces produced by thermal expansion of the charge 36 and spring 38, plus the pressure in chamber 42 acting on the diaphragm 30. Relatively high temperature gas in suction line 40 flows through chamber 42 in valve 18 and heats the body 20 and caps 29 and 32 as well as the pad 44 carried by diaphragm 30, thereby causing thermal charge 36 to produce a proportionate downward force on the valve stem 46. It will be appreciated that an upward force is exerted on the valve stem 46 when the temperature of the superheat decreases. Spring 38 develops an opposing upward force on the nut 47 and the stem 46, so that any movement of the metering valve element 48 is a function of the suction line temperature, all as conventional in the art. Variation in superheat setting can be achieved by turning nut 47 on the stem.v

A throttling mechanism or throttle valve 50 is located in the suction line upstream from chamber 42. As shown, the valve includes a cylindrical metallic body or housing 52 having an inlet end internally threaded to receive the suction line 40. The outlet end of the valve body 52 is also internally threaded to receive an apertured plug or fitting 53 which is adapted to be threadedly screwed into the thermostatic expansion valve body 20. An O-ring 51 is located between the contiguous surfaces of the plug 53 and valve body 52 to prevent refrigerant from leaking thereby. The plug 53 includes an internally enlarged portion 54 and a tapered annular portion 55 which forms the valve seat, as will be described presently.

Located on the upstream side of valve seat 55 is a temperature-responsive power operating means 56 comprising a container 58, a piston 60, and a pellet-like mass of temperature-sensitive material 62. Container 58 includes a cup-like element 64 and sleeve-like cover or tubular guide 66 suitably connected together for retention of an elastomeric diaphragm 68 and plug 70 in sealing relation to the pellet meterial 62. In operation, any temperature increase of the refrigerant vapor surrounding cup 64 causes the pellet 62 to transform from the solid state to the liquid state, thereby expanding to produce pressures on the diaphragm 68 sufficient to move plug 70 bodily.outwardly relative to sleeve 66. The piston is arranged to slide fit in the tubular guide 66 and is adapted to move between a compressed and protracted position in response to the expansion and contraction of the pellet 62. The free end of a piston is threaded as shown'at 71 and is screwed into the central aperture of a spider member 72. The free end of piston 71 includes a slot which allows for calibration of the valve setting and after the necessary adjustments have been made a lock or retention nut 73 is screwed into the threaded portion of piston 71. The spider 72 is preferably cup-shaped and includes a number of radially extending legs, and outer extremities of which join with a substantially wider annular flange. The spider 72 is preferably stamped of sheet metal or the like and is press fitted into the enlarged aperture 51 of plug 50. A relatively tight fit is ensured by the fact that a substantially large surface area is provided by the annular flange of the spider 72. A poppet valve element or member 72 is screwed onto the threaded portion provided on the free end of tubular guide 66. The surface of the valve member 74 adjacent the plug 53 is also tapered to match tapered valve seat 55. A compression spring 75 is disposed between the inner surface of the valve member 74 and the inner wall formed on the inlet end of the valve body 52. The compression spring 75 effectively surrounds the power operating means so that no additional space or length is required. The compression spring 75 is arranged to normally urge or bias the valve member 74 toward its closed position. Under normally operating conditions, the piston 71 is extended due to the liquified expanded pellet 62 so that the valve member 74 is unseated from the valve seat 55, as shown in FIG. 1. Now when the temperature of the refrigerant vapor surrounding cup 64 decreases the pellet 62 will begin to solidify and contract thereby allowing the compression spring 75 to depress the piston 71 into the container 58 so that valve member 74 moves toward the valve seat 55.

Pellet 62 preferably includes a mass of wax which undergoes solid-liquid transition in a temperature range near or spanning 32 F, as for example completely solid at 28 F and completely liquid at 39 F. Suitable waxes are commercially available for solid-liquid expansion in the desired range. Such waxes are mixtures of different hydrocarbons which produce the effective transition in wider or narrower temperature ranges according to composition of the pellet as determined by the initial fractionating and compounding, all according to known practice in the art. FIG. 3 illustrates the temperature-motion curve ofa thermostatic power means useful in practice of the invention.

Pressures produced by pellet 62 expansion can be comparatively high, as for example over 2,000 p.s.i., if the expansion process is resisted, as by holding the piston and container in their start positions. In the actual installation the pellet pressures may reach fairly' high values since the piston and container are restrained by the spring 75 and the radial friction loads between plug 70 and sleeve 66, plus the pressure difference across the valve due to the throttling action at 74. The capability of the pellet for producing relatively high forces is important in that it allows the temperatureresponsive power means to move only as a function of the suction line temperature without in any way being influenced by variations in suction line pressure. Suction line pressures are usually relatively low, on the order of 50 p.s.i. or less.

During operation of the illustrated system, the throttling element 74 will exert little, if any throttling effect as long as the suction gas temperature is above 39 F; valve member 74 is then spaced rightwardly away from seat 55, as shown. Should the temperature of the refrigerant in the suction line 40 drop below 39 F, valve member 74 will exert a progressively greater throttling effect according to how much the temperature drops, and at approximately 28 F, the member 74 will move in the direction of seat 55, thereby throttling refrigerant flow from the evaporator to the compressor.

Compressor is usually running on a continuous basis as long as the vehicle engine is running and the occupant has turned the air conditioner switch to the on position. On a continuous run basis for the compressor, the actual temperature in the passenger space can be controlled by dampers and/or variable speed fans operating on the air-stream flowing across the evaporator or reheat from any suitable source, i.e., engine cooling water, condenser cooling water, heat rejected into the condenser cooling air or any other convenient means. Assuming sufficient demand for air cooling, the evaporator 16 will be at a high enough temperature to prevent any icing on its fin surfaces. However, during low demand periods less refrigerant will be evaporated in the evaporator, and the continuously running compressor will tend to reduce the pressure and temperature in the suction line and evaporator, all in accordance with curve 76 of FIG. 2.

If the throttling valve mechanism 50 were not in the system the evaporator temperature could well drop below 32 F so that ice and frost would tend to form on the fin surfaces. The drop in temperature is due to the fact that the compressor 10 would keep pulling down the pressure of the evaporator 16 so that a resulting drop in temperature would occur. However, in actual practice ice at 32 F is rather slushy or only temporarily on the fin surfaces due to air. heating effects or air movement effects. Usually the fin temperature must get down to about 28 F before permanent ice and frost formations occur; 28 F is therefore chosen as the temperature at which throttling mechanism 50 controls the flow of refrigerant from the evaporator to the compressor.

In operation of the system with mechanism 50 installed therein, the system functions in the normal manner at evaporator temperatures above 39 F. However, should the air-cooling demand'or load be so reduced as to permit the compressor to lower the evaporator pressure below about 27 p.s.i. the corresponding drop in suction line temperature will cause material 62 to partially solidify so as to produce a throttling action by movement of poppet element 74 toward seat 55. The throttling action will cause several things to happen, as follows: first, the pressure in the evaporator will be higher than if no throttling had taken place, and second, the superheat in chamber 42 will be somewhat higher than otherwise when chamber 36 is system charged. Thus, the throttling valve mechanism 50 prevents the compressor 16 from reducing the temperature of the evaporator 10 to a level which would cause ice and frost to form on the surfaces of the tins of the evaporator.

The throttling mechanism 50 may be located on either side of chamber 42 or may be situated in any convenient location in the suction line. It is preferred to wholly or partially isolate the thermal charge 36 from the evaporator temperatures during the throttling periods. This isolation effect is advantageous in that charge 36 assumes an artificially high temperature for more fully opening the metering element 48. In addition, throttling reduces the pressure in chamber 42 which ordinarily tends to resist the downward pressure exerted by thermal charge 36, dependent upon the material in charge 36, to thereby increase the downward force on meter element 48 to allow more full opening of that element. The action tends to produce a flooding action in the evaporator, both because element 48 is feeding the evaporator with liquid and because element 74 is restricting the escape or vapor from the evaporator. Such flooding tendency raises the evaporator pressure and evaporator temperature, thus producing a deicing and/or icer-present action on the evaporator surfaces. The temperature-pressure relationship will follow line 78 rather than the normal curve 76 as shown in FIG. 2.

It will be understood that the operation is a modulating action wherein throttling and pressure-temperature changes may be gradual without full throttling or full opening of element 74. Also, the described temperature of 28 F normal full-throttle and 39 F normal fullopen are somewhat arbitrary; useful results may be achieved using different temperature ranges. ln gen- I eral, however, it is preferred to choose temperatures which are just above the evaporator fin icing level; this lets the evaporator have more cooling capacity with a given surface area, thereby permitting a smaller evaporator for a given duty.

It is of some importance that power operating means 56 be insensitive to pressure variations in the suction line, and that power operating means 56 have sufficient force capability to open and close the throttling element 74 independent of the pressure drop across seat 55. If a low force power means such as a bimetal or liquid-charged bellows were used in lieu of power means 56 the pressure drop across the valve seat would tend to increase the throttling effect to the undesirable extent, sufficient to prevent normal operation of the system. Therefore, the thermostatic power means must be pressure-insensitive for proper results.

The drawings show power operating means 56 as a wax-charged element wherein temperature decrease produces contraction of pellet 62. It is contemplated that the charge could be water instead of wax, in which case a temperature decrease to a value below approximately 32 F would produce a change of state from liquid (water) to solid (ice) with an accompanying expansion of the charge. The relationship between the valve element and seat would be such as to produce throttling on expansion of the charge.

An advantage is realized by disposing the compression spring 75 between the valve member 74 and the inner wall of the inlet side of the valve body. It will be noted that a separate space is not required for the spring 75 since it effectively surrounds the power operating means 56, and therefore, the length of the valve body 57 may be effectively shortened. Such a space saving feature is very desirable, particularly in, an automotive application where space is at a premium.

On hot days, the temperature under the hood of a motor vehicle may be l75 F or above which can cause the piston 71 to be extended beyond its normal length of travel. This over-travel does not adversely affect the unique arrangement as shown in FIG. 1 since the spring 75 will allow further movement of the power operating means 56 so that no damage will occur to the valve parts during periods of overheating.

It has also been found highly advantageous to place the container 64 adjacent to the inlet side of valve mechanisms rather than adjacent its outlet side. Further, with the disposition shown, the container is exposed to the suction line from the evaporator which is the condition to be sensed by the temperature sensitive material 62. Thus, more effective results and quicker response to changing evaporator conditions will be produced with the power operating means disposed as shown.

An additional benefit of utilizing the throttle valve mechanism 50 is that the compressor 10 is not required to work as hard as compressors in previous refrigerating systems in that the head or discharge pressure of the compressor is reduced in proportion to the amount of throttling action.

It will be appreciated that while this invention finds particular utility in automotive air conditioner systems, it is readily evident that the invention is not limited thereto but may be employed in other refrigerating systems and in other environmental settings. It will also be apparent that various alterations, modifications and changes can be made to the presently described invention, and therefore, it is understood that all changes, equivalents, and modifications falling within the spirit and scope of the present invention are herein meant to be included in the appended claims.

Having thus described our invention what we claim l. The combination for automatically regulating evaporator temperature in a refrigerating system of a throttle valve for throttling the flow of refrigerant fluid from an evaporator in a refrigerating system with refrigerant fluid metering means for controlling the flow of refrigerant fluid to an evaporator, said throttle valve comprising a valve body receiving said refrigerant fluid from an evaporator and, having openings near its opposite ends to allow flow of refrigerant fluid therethrough, a power operating means mounted within said valve body, said power operating means including a container having a mass of material sensitive to a limited range of temperatures which expands and contracts in accordance with the temperature of the refrigerant fluid, said container being disposed directly in the path of flow of said refrigerant fluid through said valve body, so that said valve responds immediately to changes in temperature of said refrigerant fluid, said power operating means including a slidable member cooperatively associated with said container and arranged to be reciprocated in accordance with the expansion and contraction of said mass of said material sensitive to a limited range of temperatures, a valve member operated by said power operating means and arranged to move away from and toward a valve seat in accordance with the reciprocation of said slidable member, and a biasing spring normally urging said valve member toward said seat.

2. The combination of claim 1 wherein said container is disposed adjacent the opening in one end of said valve body and said valve member is disposed adjacent the opening in the opposite end of said valve body.

3. The combination of claim 1, wherein said biasing spring is situated between said valve member and a wall formed near the opening in one end of said valve body and surrounds said power operating means.

4. The combination of claim 1, wherein said slidable member is a piston having its free end connected to a spider member which is fitted into the opening at one end of said valve body.

5. The combination of claim 1, wherein said valve member is securely fixed to said container of said power operating means.

6. The apparatus of claim 4, wherein said free end of said piston is adjustably connected to said spider memher.

7. The combination of claim 1, wherein said mass of material sensitive to a limited range of temperatures is a wax which undergoes a solid-liquid transition in accordance with the temperature of the fluid.

8. The combination of claim 1 wherein said narrow range of temperatures to which said mass of material is sensitive to operate said valve to modulate the flow of said refrigerant fluid through said valve body is of the order of approximately 28F. to 39F.

9. The combination of claim 1 wherein said refrigerant fluid metering means includes a thermostatic expansion valve. 

1. The combination for automatically regulating evaporator temperature in a refrigerating system of a throttle valve for throttling the flow of refrigerant fluid from an evaporator in a refrigerating system with refrigerant fluid metering means for controlling the flow of refrigerant fluid to an evaporator, said throttle valve comprising a valve body receiving said refrigerant fluid from an evaporator and, having openings near its opposite ends to allow flow of refrigerant fluid therethrough, a power operating means mounted within said valve body, said power operating means including a container having a mass of material sensitive to a limited range of temperatures which expands and contracts in accordance with the temperature of the refrigerant fluid, said container being disposed directly in the path of flow of said refrigerant fluid through said valve body, so that said valve responds immediately to changes in temperature of said refrigerant fluid, said power operating means including a slidable member cooperatively associated with said container and arranged to be reciprocated in accordance with the expansion and contraction of said mass of said material sensitive to a limited range of temperatures, a valve member operated by said power operating means and arranged to move away from and toward a valve seat in accordance with the reciprocation of said slidable member, and a biasing spring normally urging said valve member toward said seat.
 2. The combination of claim 1 wherein said container is disposed adjacent the opening in one end of said valve body and said valve member is disposed adjacent the opening in the opposite end of said valve body.
 3. The combination of claim 1, wherein said biasing spring is situated between said valve member and a wall formed near the opening in one end of said valve body and surrounds said power operating means.
 4. The combination of claim 1, wherein said slidable member is a piston having its free end connected to a spider member which is fitted into the opening at one end of said valve body.
 5. The combination of claim 1, wherein said valve member is securely fixed to said container of said power operating means.
 6. The apparatus of claim 4, wherein said free end of said piston is adjustably connected to said spider member.
 7. The combination of claim 1, wherein said mass of material sensitive to a limited range of temperatures is a wax which undergoes a solid-liquid transition in accordance with the temperature of the fluid.
 8. The combination of claim 1 wherein said narrow range of temperatures to which said mass of material is sensitive to operate said valve to modulate the flow of said refrigerant fluid through said valve body is of the order of approximately 28*F. to 39*F.
 9. The combination of claim 1 wherein said refrigerant fluid metering means includes a thermostatic expansion valve. 